"I am an outsider, the only candidate who isn't a career politician," said Greene, 55. "I've been a job creator. I've worked in the economy myself. I'm the only one among the four of us who ever signed the front side of a paycheck. Those guys have only signed the backs of paychecks."

His colorful profile — Mike Tyson was best man at his 2008 wedding, ex-Hollywood madam Heidi Fleiss lived in his guest house after prison, and he made many of his millions betting on the housing collapse that killed Florida's economy — normally would make a candidate like Greene a long shot.

But in a race where Democratic front-runner Kendrick Meek is little known to most voters and Gov. Charlie Crist's nonpartisan candidacy has turned the campaign upside down, Greene's ability to saturate Florida TV with commercials could make him a major contender along with Republican Marco Rubio.

"I'll spend whatever it takes to get my message out and to be competitive with these career politicians," Greene told the Herald/Times in a telephone interview. "I'm not going to take a penny of special interest money."

Considering that Forbes last year estimated Greene's net worth at $1.25 billion, shunning special interest money and limiting donations to $100 or less is no big sacrifice.

Greene, who once ran unsuccessfully for Congress in California as a Republican, said he is the personification of the American dream and that his wealth allows him to focus on what matters most.